When inspect.getframeinfo() tries to collect lines of context it never shows the first line (unless context is as big as the number of lines in the file).

The relevant code is

        start = lineno - 1 - context//2
        try:
            lines, lnum = findsource(frame)
        except IOError:
            lines = index = None
        else:
-->         start = max(start, 1)
            start = max(0, min(start, len(lines) - context))
            lines = lines[start:start+context]
            index = lineno - 1 - start

I think that

            start = max(start, 1)

should be replaced by

            start = max(start, 0)

For some reason getframeinfo() (and the functions which use it) don't seem to be tested by the testsuite...

Looking into this now. Should have a patch either later today or tommorow.

Also, would you mind posting an example? I'm having trouble replicating.

Nevermind, replicated it. Changing start = max(start, 1) to start = max(start, 0) DOES fix. Writing a test case now.

Here's a patch. Very, very simple, just changed that one line in inspect.py and wrote a highly primitive test case for inspect.getframeinfo. The test isn't actually testing the primary functionality right now, just this one bug. I can probably write more expansive coverage later, but in the interest of an expeditious reply I'm submitting now.

I have just hit this bug and independently invented the exact fix of changing the zero for a one. Any chance of getting this merged?

New changeset 15454cad5f27 by Berker Peksag in branch '3.5':
Issue #15812: inspect.getframeinfo() now correctly shows the first line of a context
https://hg.python.org/cpython/rev/15454cad5f27

New changeset 410caf255a09 by Berker Peksag in branch '3.6':
Issue #15812: Merge from 3.5
https://hg.python.org/cpython/rev/410caf255a09

New changeset 803c3c21c3bc by Berker Peksag in branch 'default':
Issue #15812: Merge from 3.6
https://hg.python.org/cpython/rev/803c3c21c3bc

Thanks for the patch Sam and thanks for the ping Peter!

start is bounded to 0 twice.

    start = max(start, 0)
    start = max(0, min(start, len(lines) - context))

The first line can be just removed. Or two above lines can be rewritten as:

    start = min(start, len(lines) - context)
    start = max(start, 0)

New changeset 2b6bdd6cd3f8 by Berker Peksag in branch '3.5':
Issue #15812: Delete redundant max(start, 0)
https://hg.python.org/cpython/rev/2b6bdd6cd3f8

New changeset 7cbcee0c53e3 by Berker Peksag in branch '3.6':
Issue #15812: Merge from 3.5
https://hg.python.org/cpython/rev/7cbcee0c53e3

New changeset 5b0dee884b0b by Berker Peksag in branch 'default':
Issue #15812: Merge from 3.6
https://hg.python.org/cpython/rev/5b0dee884b0b

You're right. Thanks for the review, Serhiy!